Communication of real ideas, thoughts and feelings is fundamentally hard. It takes committed, enduring effort to build the narrow, delicate bridge between.
Intuitive and unspoken understanding of others is a critical part of any human relationship and there should be expectations there.
However it takes time, ongoing communication, vulnerability and risk taking (appropriate to the relationship type and depth) in order to build and maintain any remotely accurate model of the internal states. This need grows in proportion to the amount of care between the individuals in question.
No one will ever be 100% correct about another’s mental state 100% of the time, no matter how intense the feelings or how much time is spent together.
Relying on assumptions and fictional constructs (eg romanticism) of how things should be is a is a recipe for disaster and resentment.